Increase In Absorption Rate Research Articles

Bulk resonance absorption induced by relativistic effects in laser-plasma interaction

Resonance absorption in relativistic laser-plasma interaction is studied via two-dimensional particle-in-cell simulation. As the laser intensity increases from the linear regime, the absorption rate first decreases due to relativistic modulation of the electron plasma oscillations excited at the mode conversion layer. However, the trend reverses after a critical intensity. The reversal can be attributed to the fact that the relativistic critical layer depends on the local intensity of the laser pulse, so that instead of occurring in a thin layer, resonance absorption occurs in a plasma bulk region, leading absorption rate increase. The reflected-light spectrum also shows broadening and splitting of the harmonics at high laser intensities, which can be attributed to critical-surface oscillations driven by the laser ponderomotive force.

Kinetics of leather dyeing pretreated with enzymes: Role of acid protease

In the present investigation, kinetics of dyeing involving pretreatment with acid protease has been presented. Application of acid protease in dyeing process resulted in increased absorption and diffusion of dye into the leather matrix. Enzyme treatment at 1% concentration, 60 min duration and 50 °C resulted in maximum of 98% dye exhaustion and increased absorption rate constants. The final exhaustion ( C ∞) for the best fit of CI Acid Black 194 dye has been 98.5% with K and r 2 values from the modified Cegarra-Puente isotherm as 0.1033 and 0.0631. CI Acid Black 194 being a 2:1 metal complex acid dye exhibited higher absorption rate than the acid dye CI Acid Black 210. A reduction in 50% activation energy calculated from Arrhenius equation has been observed in enzyme assisted dyeing process of both the dyes that substantiates enhanced dye absorption. The absorption rate constant calculated with modified Cegarra-Puente equation confirm higher rate constants and faster kinetics for enzyme assisted dyeing process. Enzyme treated leather exhibited richness of color and shade when compared with control. The present study substantiates the essential role of enzyme pretreatment as an eco-friendly leather dyeing process.

Children's toxicology from bench to bed - Liver Injury (1): Drug-induced metabolic disturbance - Toxicity of 5-FU for pyrimidine metabolic disorders and pivalic acid for carnitine metabolism -

Congenital disorders of metabolism show a wide spectrum of symptoms as a consequence of impairment of a certain metabolic pathway by mutated enzymes resulting in abnormal accumulation of enzyme substrates, deficiency of expected products, and abnormal burden to collateral metabolic pathways, etc. However, in some occasions, depending on which pathway up to what degree of disturbance, it can be asymptomatic until a certain kind of burden is placed on to the patient. Enzyme deficiency involved in pyrimidine degradation, such as Dihydropyrimidine dehydrogenase (DPD) and Dihydropyrimidinase (DHP), has been reported with convulsion or autism as symptoms, but many asymptomatic cases are also reported. However, when the patients are treated with 5-fluorouracil, a pyrimidine analogue anticancer drug, lethal side-effects can be seen even in asymptomatic patients. Some oral cephem antibiotics have pivalic acid side chain to increase absorption rate at intestine. These antibiotics degrade into active antibiotics and pivalic acid at the intestinal wall. This pivalic acid is carnitine-conjugated and excreted into urine. Carnitine acts as a carrier of long chain fatty acid to mitochondria and to beta-oxidation, thus an important molecule for energy production by beta-oxidation and maintenance of mitochondrial function. Because of this, long term administration of such antibiotics could induce depletion of carnitine from the body and lead to low ketotic hypoglycemia, convulsion and consciousness disturbance. This paper reports some possible serious side effects closely linked to drug metabolism.

‘Kardinal’ Rose Exhibits Growth Plasticity and Enhanced Nutrient Absorption Kinetics Following Nitrate, Phosphate, and Potassium Deprivation

Plant internal nutrient status is known to influence the kinetics of nutrient absorption, but little on this relationship has been reported for roses (Rosa spp. L.). The objectives of this experiment were to determine the influence of NO3, PO4, and K deprivation on plant tissue concentrations and relative growth rates and to quantify the influence of nutrient deprivation on absorption kinetic parameters. Rose plants growing in solution culture were deprived of N, P, or K for 0 to 20 days to establish differing tissue concentrations. Absorption kinetics were then determined based on the rate of NO3, PO4, or K depletion from solution over a range of concentrations. The data were fit to a modified Michaelis-Menten equation to account for the influence of internal nutrient status on absorption kinetics. Plants deprived of the nutrients for up to 20 d did not show significantly reduced root or plant fresh weight as compared with control plants. Plant tissue concentrations differed significantly by deprivation treatment and varied from 1.4% to 2.3% for N, 0.22% to 0.35% for P, and from 1.0% to 2.0% for K. Plants deprived of NO3, PO4, and K subsequently showed increased absorption rates. This was primarily expressed as an increased maximum absorption rate for NO3 and PO4. In contrast, K-deprived plants primarily exhibited an increased affinity (decreased Km) for K. The results demonstrate the plasticity of rose plants to grow and absorb nutrients under varying internal nutrient concentrations. This work quantifies the influence of rose plant nutritional status on the kinetics of NO3, PO4, and K absorption. The knowledge would be useful to improve models for providing decision support for fertilization based on plant growth rates and internal nutrient status.

Relevance of Absorption Rate and Lag Time to??the Onset of Action in Migraine

The objective of this analysis was to simulate the performance of oral triptan formulations with varying absorption characteristics and their impact on the onset and magnitude of the antimigraine effect using a Markov model for migraine attacks. Sumatriptan pharmacokinetic data were obtained from clinical pharmacology studies in which marketed solid formulations were administered. Based on a population pharmacokinetic model, mean concentration-time profiles were generated by varying the absorption rate constant and lag time. Subsequently, the simulated profiles were evaluated in a disease model of migraine to predict the onset and duration of the effect (the pain-free, pain-relief response). Based on a therapeutic dose of 50 mg of sumatriptan, a maximum gain in the pain-free response of 12% was achieved with an increased absorption rate. This gain in the response was reached approximately 0.5 hours after administration. A decrease only in the lag time with respect to the currently available formulations (i.e. 0.24 hours) resulted in a maximum gain of 5% in the pain-free response, which in contrast may not be interpreted as clinically relevant. Model-based predictions suggest that increases in the absorption rate of the currently marketed oral formulation of sumatriptan result in a gain in the pain-free response that is both clinically and statistically relevant.

Absorption of carbon dioxide by the absorbent composed of piperazine and 2-amino-2-methyl-1-propanol in PVDF membrane contactor

This paper tests the performance of microporous polyvinylidinefluoride (PVDF) hollow fiber in a gas absorption membrane process (GAM) using the aqueous solutions of piperazine (PZ) and 2-amino-2-methyl-1-propanol (AMP). Experiments were conducted at various gas flow rates, liquid flow rates and absorbent concentrations. Experimental results showed that wetting ratio was about 0.036% when used with the aqueous alkanolamine solutions, while that was 0.39% with aqueous piperazine solutions. The CO 2 absorption rates increased with increasing both liquid and gas flow rates at N Re < 20. The increase of the PZ concentration showed an increase of absorption rate of CO 2. The CO 2 absorption rate was much enhanced by the addition of PZ promoter. The resistance of membrane was predominated as using a low reactivity absorbent and can be neglected as using absorbent of AMP aqueous solution. The resistance of gas-film diffusion was dominated as using the mixed absorbents of AMP and PZ. An increase of PZ concentration, the resistance of liquid-film diffusion decreased but resistance of gas-film increased. Overall, GAM systems were shown to be an effective technology for absorbing CO 2 from simulated flue gas streams, but the viscosity and solvent–membrane relationship were critical factors that can significantly affect system performance.

Soaking behaviour and milky extraction performance of tiger nut ( Cyperus esculentus) tubers

Three diameter sizes ( D < 0.5 cm, 0.5 cm < D < 1 cm and D > 1 cm) of tiger nut ( Cyperus esculentus) tubers growing in Cameroon (Central Africa) were soaked between 20 °C and 100 °C until water content equilibrium, and pressed for extraction of milky beverage (“horchata”). Application of Peleg model was investigated for predicting water absorption of tubers during soaking. The model showed to predict kinetics of the tiger nut soaking. The Peleg absorption rate constant ( k 1) decreased as temperature increased, indicating increase in absorption rate with temperature, with a discontinuity at 60 °C. The water absorption capacity ( k 2) was relatively stable, but displayed the same discontinuity at 60 °C. The extraction yield and the insoluble extract content of the milky beverage increased with temperature, while its soluble extract content decreased in the same conditions. These trends were attributed to the weakening of cell walls of the tubers at higher soaking temperature, generating high level of material transfer, as justified by the very low values of k 1 at high soaking temperature.

Accelerated Lipid Absorption in Mice Overexpressing Intestinal SR-BI

Dietary cholesterol absorption contributes to a large part of the circulating cholesterol. However, the mechanism of sterol intestinal uptake is not clearly elucidated. Scavenger receptor class B type I (SR-BI), major component in the control of cholesterol homeostasis, is expressed in the intestine, but its role in this organ remains unclear. We have generated transgenic mice overexpressing SR-BI primarily in the intestine by using the mouse SR-BI gene under the control of intestinal specific "apoC-III enhancer coupled with apoA-IV promoter." We found SR-BI overexpression with respect to the natural protein along the intestine and at the top of the villosities. After a meal containing [(14)C]cholesterol and [(3)H]triolein, SR-BI transgenic mice presented a rise in intestinal absorption of both lipids that was not due to a defect in chylomicron clearance nor to a change in the bile flow or the bile acid content. Nevertheless, SR-BI transgenic mice showed a decrease of total cholesterol but an increase of triglyceride content in plasma without any change in the high density lipoprotein apoA-I level. Thus, we described for the first time a functional role in vivo for SR-BI in cholesterol but also in triglyceride intestinal absorption.

Effect of Water Absorption Rates on Fracture Toughness of Sisal Textile Fiber Reinforced Composites

Using natural fibers that are inexpensive, lightweight and biodegradable, as the reinforcement for composites is difficult due to their poor interfacial properties between hydrophilic fiber and hydrophobic polymer matrices. It is necessary to evaluate fracture toughness of natural fiber reinforced composites according to water absorption rates to improve mechanical performance of those. In this study, compact tension fracture test was conducted to evaluate fracture toughness with the various specimens. The value of fracture toughness has the tendency to decrease as water absorption rate increases. And different surface treatment methods and different polymer matrices have influence on the value of fracture toughness.

The digestive performance of mammalian herbivores: why big may not be that much better

ABSTRACT 1. A traditional approach to the nutritional ecology of herbivores is that larger animals can tolerate a diet of lesser quality due to a higher digestive efficiency bestowed on them by comparatively long ingesta retention times and lower relative energy requirements. 2. There are important physiological disadvantages that larger animals must compensate for, namely a lower gut surface : gut volume ratio, larger ingesta particle size and greater losses of faecal bacterial material due to more fermentation. Compensating adaptations could include an increased surface enlargement in larger animals, increased absorption rates per unit of gut surface, and increased gut motility to enhance mixing of ingesta. 3. A lower surface : volume ratio, particularly in sacciform forestomach structures, could be a reason for the fact that methane production is of significant scope mainly in large herbivores and not in small herbivores with comparably long retention times; in the latter, the substrate for methanogenesis – the volatile fatty acids – could be absorbed faster due to a more favourable gut surface : volume ratio. 4. Existing data suggest that in herbivores, an increase in fibre digestibility is not necessarily accompanied by an increase in overall apparent dry matter digestibility. This indicates a comparative decrease of the apparent digestibility of non‐fibre material, either due to a lesser utilization of non‐fibre substrate or an increased loss of endogenous/bacterial substance. Quantitative research on these mechanisms is warranted in order to evaluate whether an increase in body size represents a net increase of digestive efficiency or just a shift of digestive focus.

Experiments on axisymmetric oscillating water jets: absorption of ammonia in presence of n-pentanol

The competing effects of pentanol adsorption and ammonia absorption on the shape of axisymmetric oscillating water jets are studied experimentally and interpreted qualitatively. While there is no significant influence of the absorption process on pure water jets, considerable change in jet length and deviation from sinusoidal evolution of surface oscillation in presence of n-pentanol is observed, accompanied by an increase in absorption rate. Hence dependence of jet shape on interfacial convection is shown. The effects of pentanol adsorption, surface elasticity of a pentanol surface film and nonuniform velocity distribution on jet stability are discussed quantitatively.

Study of Anthocyanin Pigments Produced During Pickled Red Cabbage "Sauerkraut" Production

In an effort to determine the anthocyanin (AN) pigment yield during the maturation of pickled red cabbage, the determination of pH, acid content, salt level, absorbance, degree of browning and color tone and analysis by LC/MS and HPLC were conducted. The results indicate that the pickled red cabbage maturation method may be used in preparing AN pigments. (1) During the maturation of pickled red cabbage, a pH decrease accompanied an increase in acid content, and an increase in absorption rate was observed on days 5-9. No notable browning ensued and the cabbage's color tone became deep red, which progressively darkened with maturation. (2) The structures of red cabbage AN pigments were estimated to be as follows : P1 : cyanidin [Cy] 3-O-(2-O-beta-D-glucopyranosyl [Glc])-beta-D-Glc]-5-O- (beta-D-Glc)]; P6: [Cy-3-O-(2-O-(6-O-p-coumaryl [p C]-beta-D-Glc))-5-O-(beta-D-Glc)]; P7: [Cy-3-O-(2-O-(2-O-sinapyl [Si]-beta-D-Glc))-5-O-(beta-D-Glc)]; P9: [Cy-3-O-(6-O-pC-2-O-(2-O-Si-beta-D-Glc))-(5-O-(beta-D-Glc)); P10: [Cy-3-O-(6-O-ferulyl [Fr]-2-O-(2-O-Si-beta-D-Glc))-5-O-(beta-D-Glc)]; and P11: [Cy-3-O-(6-O-Si-2-O-(2-O-Si-beta-D-Glc))-5-O-(beta-D-Glc)]. (3) The yield of total AN pigments was highest on days 5-9 of the maturation of pickled red cabbage. Among the red cabbage AN pigments, P1, a nonacylated AN, had the highest yield, which remained unchanged from days 0 through 21. However, the yields of P6 and P7, which are acylated AN pigments, increased up to day 9. These three pigments comprised the principal AN pigments of pickled red cabbage.

Photoluminescent Enhancement of Ruthenium Complex Monolayers by Surface Plasmon Resonance of Silver Nanoparticles

AbstractThe photoluminescence intensity from a bis (2,2'-bipyridine)-(5-isothiocyanato-phenanthroline) Ruthenium (RuBICP) monolayer covalently bound to a glass substrate is found to be enhanced up to 20 times when silver nanoparticles are deposited on top. The emission spectra are blue shifted by interactions with the silver nanoparticles. Field enhancement is found to be able to enhance the radiative decay rate by over three orders of magnitude but fewer than 2 % of the molecules in the sample experience this large enhancement. Increased absorption rates also increase the luminescence but to a much smaller degree.

Energetic balance of infaunal ( Mulinia edulis King, 1831) and epifaunal ( Mytilus chilensis Hupé, 1854) bivalves in response to wide variations in concentration and quality of seston

Mulinia edulis and Mytilus chilensis are commercially important filter feeding bivalves, which occur in intertidal benthic habitats of southern Chile. These environments are subject to large fluctuations in quantity and quality of suspended particulate matter (seston), due mainly to the resuspension of benthic sediments by the action of winds and tides. In spite of variations in the availability of suspended food, these species demonstrate rapid growth rates during most of the year. Laboratory tests feeding were carried out with different artificially prepared diets in order to understand the physiological compensations effected by these bivalves in response to fluctuations of suspended particulate matter. A total of 48 different combinations of microalgae ( Isochrysis galbana) and natural sediment collected from the intertidal zone were tested, having concentrations ranging from 1.9 to 203 mg l −1, and containing 18–91% organic matter. Absorption, oxygen consumption and excretion were measured in both species for each experimental diet in order to calculate the physiological index scope for growth. Temperature was maintained constant at 14 °C and salinity at 30‰. Both species demonstrated a high degree of physiological plasticity, which allowed them to maintain a positive scope for growth under most dietary conditions. The epifaunal species M. chilensis was better adapted to an environment having intermediate quantities of seston (50–150 mg l −1 and 40–60% organic matter); its scope for growth was high due to its high rate of energy absorption. The infaunal M. edulis was not well adapted with very low concentrations and quality of food (<3 mg l −1 and <25% organic material), and had a negative scope for growth under these conditions due to a low absorption rate and high energy losses through oxygen consumption and excretion. However, this species was well adapted to high concentrations and/or high quality of seston (>100 mg l −1 and 60% organic matter) where it showed a higher scope for growth due to an increase in absorption rate. M. chilensis showed better scope for growth in comparison with M. edulis, explainable by its greater feeding capacity, suggesting that the epifaunal species has an adaptive advantage through being able to better compete for available food, especially when there are low concentrations of seston in the water.

Hepatic metabolism of propionate and methylmalonate in growing lambs

The hepatic extraction ratio of propionate and the net hepatic flux of methylmalonate (MMA) were investigated in six Suffolk lambs (32.7±1.7 kg BW) implanted with catheters in a mesenteric artery and in the portal, hepatic, and ruminal veins and a cannula in the rumen. The lambs were fed a pelleted barley-based diet (1.1 kg DM per day) and subjected to three intravenous infusion protocols separated by at least 7 days: saline (C; control), butyrate (B; 0.2 mmol/h/kg BW) or lactate (L; 0.96 mmol/h/kg BW). The solutions were infused continuously into the ruminal vein for 13 h. At the same time as the intravenous infusion treatments, propionate (1.78 mmol/h/kg BW) was infused intraruminally for 4 h starting 4 h after the initiation of the experimental protocol. Arterial, portal and hepatic blood samples were obtained during the last 10 h of the infusion protocol. Blood flow was measured by down stream dilution of p-aminohippuric acid. The hepatic extraction ratio of propionate decreased from 85±3 to 75±1% after intraruminal infusion of propionate and the net splanchnic appearance of propionate increased threefold with the doubling of the net portal appearance of propionate. Intravenous infusion of lactate or butyrate did not affect the hepatic extraction ratio or net splanchnic flux of propionate. The net portal appearance, net hepatic flux and net splanchnic appearance of MMA were not ( P>0.10) different from zero in all situations. The arterial concentration of MMA increased with increasing absorption rate of propionate but remained below 2 μmol/l throughout the experiment. The results of the present study do not support the hypothesis that the MMA possibly incorporated into methyl-branched chain fatty acids in adipose tissue of intensively-reared lambs is of hepatic origin.

Comparative Population Pharmacokinetic‐Pharmacodynamic Analysis for Piroxicam‐β‐Cyclodextrin and Piroxicam

Piroxicam (Feldene) is indicated for osteoarthritis and rheumatoid arthritis but not analgesia due to its delayed onset of pain relief. Piroxicam-beta-cyclodextrin (PBCD) was developed for pain indication by virtue of the increased absorption rate of piroxicam. Forty-eight patients received a single dose of PBCD or Feldene (10, 20, and 40 mg) in a randomized study, and piroxicam plasma concentration and pain relief were measured. The purpose of the study was to investigate the PK-PD relationship of piroxicam, determine the optimal dose, and evaluate the effect of increased absorption rate on analgesic effect of piroxicam for the pain model studied. The pharmacokinetic data were best described by a two-compartment model with first-order absorption. The absorption rate of PBCD (5/h) was faster than Feldene (1.41/h). Pain relief was found to be increasing with drug concentration in a hypothetical effect compartment (Emax model). The estimated half-life of the equilibration between plasma and effect site was about 2.34 hours. Monte Carlo simulation showed that the time when at least 50% of the patients have a 75% probability of achieving meaningful pain relief (pain intensity difference (PID > or = 1) for PBCD and Feldene at a dose of 20 mg was about 0.5 and 1.5 hours, respectively. PBCD demonstrated an advantage with an onset of pain relief 1 hour earlier than Feldene.

Acute and acclimated digestive responses of the cockle Cerastoderma edule (L.) to changes in food quality and quantity

Cockles Cerastoderma edule were fed two different concentrations ( approximately 0.8 and 2 mm(3) l(-1)) of two diets with different qualities ( approximately 10 and 60% of organic content) which were achieved by mixing different proportions of ashed silt particles with cells of the microalgae Tetraselmis suecica. Clearance, ingestion and absorption rates of organic matter and biochemical components were measured after 3 days (acute response) and 11 days (acclimated response) of exposure to the diets. With low quality diets cockles were found to reject part of the filtered matter ( approximately 25-35%) through pseudofaeces production both in the acute and acclimated responses. In the acute response, absorption rate of organic matter was positively dependent on food quality and quantity, but the physiological response to increasing food concentrations differed with food quality: with low qualities, increasing absorption rate resulted from the simultaneous increase of clearance ( approximately 2 times) and ingestion rate ( approximately 4 times) as well as absorption efficiency of organic matter ( approximately 22%). However, those fed high qualities, were found to compensate increasing food concentration by reducing ( approximately 50%) clearance rate. The resulting moderate increase of ingestion rate ( approximately 1.6 times) was accompanied with a reduction in absorption efficiency ( approximately 20%). Irrespective of food quality and quantity, protein and lipids were absorbed, respectively, with the highest (from 61.7 to 80.0%) and the lowest (from 42.6 to 66.8%) efficiency. Acclimated response was entirely affected by food quality: with low qualities, cockles greatly improved the energetic intake from available ration ( approximately 4 and 2 times, with low and high food concentrations, respectively). Both preingestive and digestive mechanisms were involved in this response: at the preingestive level, clearance rate and preingestive selection efficiency were significantly increased. At the digestive level, cockles were capable of maintaining absorption efficiency of organic matter with rising ingestion rate. On the contrary, acclimation to high quality diets brought about no significant increase in organic absorption rate: with low ration, clearance rate was kept constant, whereas with high ration the increase in clearance and ingestion rate ( approximately 2 times) promoted a compensatory reduction in absorption efficiency. However, the biochemical composition of the absorbed matter was found to be absolutely modified, both at low and high food rations, due to an strong reduction of lipid absorption efficiency. The observed modifications of absorption rate and/or the biochemical composition of the absorbed matter suggests the capability of cockles to adjust the digestive performance.

Downregulation of ileal bile acid absorption in bile-duct-ligated rats

Background/Aims: Accumulation of toxic bile acids in cholestasis contributes to liver injury and depends on their synthesis, secretion and intestinal absorption. In the present study, we investigated the effect of cholestasis on the active ileal absorption of bile acids in vivo and the adaptation of transporters involved in ileal bile acid absorption. Methods: Male Wistar rats underwent ligation of the common bile duct or biliary diversion. Sham-operated rats served as controls. Active ileal bile acid absorption of taurocholate was measured by an intestinal perfusion technique. Transporter mRNA levels of the Na +/bile acid cotransporting protein (IBAT), ileal lipid binding protein (ILBP) and organic anion transporter subtype 3 (Oatp3) and protein expression of IBAT and ILBP were determined in the distal ileum. Results: After bile duct ligation the intestinal absorption rates of taurocholate were lower ( p<0.05) and after biliary diversion absorption rates were higher compared to sham-operated animals ( p<0.05). The absorption rates were inversely correlated to serum bile acid concentrations. Levels of IBAT-, ILBP- and Oatp3- mRNA were not different between the groups. However, in cholestatic rats, the expression of the 99-kDa dimer of IBAT was decreased compared to controls ( p<0.05), whereas the 46-kDa monomeric protein of IBAT and the expression of ILBP was unchanged. After biliary diversion a similar pattern of protein expression was observed, despite an increased absorption rate. Conclusions: Cholestasis leads to a decreased active ileal absorption of taurocholate. The changes in protein expression may not account for the different absorption rates. The intestinal absorption of bile acids seems to be regulated by their systemic concentration.

Zur Penetration und Permeation von Na+- und Mg2+-lonen aus verdünnten und konzentrierten Lösungen bei Human- und Schweinehaut - Ein Beitrag zur Psoriasisforschung

The mineral composition of human and pigskin is quite similar. For pigskin, proportionality is found between the concentration of Na+-ions in the bath and the amount of penetrated as well as permeated Na+-ions up to a concentration of 12 g NaCl/100ml and an absorption rate of 0.089 µ/cm2 h. Skin irritated by DMSO or rupture reveals proportionality up to 30 g NaCl/ 100 ml and an increased absorption rate of 0.377 or 0.847 µ/ cm2 h, respectively. Mg2+-ions penetrate and permeate to a lesser degree than Na+ions.

How to convert from traditional cyclosporine to the microemulsion formulation in stable renal transplant patients?

How to convert from traditional cyclosporine (CSA) to the microemulsion formulation in stable renal transplant patients is still a matter of debate. The present study was designed to evaluate the effects of changeover from traditional Sandimmune to Neoral formulation at two dose‐ratio conversions on CSA pharmacokinetics, safety and tolerability particularly in terms of renal function. Thirty outpatients regularly followed at our Clinical Research Center were randomized to 1:1 or 1:0.75 dose‐ratio conversion and assigned to the two groups according to a comparable renal function and time post‐transplant. Patients underwent CSA pharmacokinetic evaluation and renal function measurements (GFR and RPF) before, at day 15, and at month 6 after conversion to Neoral formulation. More consistent CSA concentration‐time profiles with Neoral than traditional formulation were obtained at the two time points of evaluation after conversion. At 1:1 dose‐ratio conversion an increased absorption rate, reflected by a shorter time to maximum blood CSA concentration (Tmax), and a greater bioavailability, as shown by an increase in the peak CSA concentration (Cmax) and the 12‐h exposure to drug defined by the area under the time‐concentration curve (AUC0→12h) was found 15 d and 6 months after conversion to Neoral formulation. A similar AUC as compared with traditional Sandimmune was observed in those patients randomized to receive a 25% lower dose of Neoral formulation. All of patients defined as ‘low’ absorbers became ‘high’ absorbers as early as 15 d after conversion to Neoral formulation at 1:1 or 0.75 dose‐ratio regimen. Overall mean GFR was unchanged in both conversion regimens during the 6 months of follow‐up. However, there was a tendency to lower GFR even in some patients randomized to 1:0.75 conversion but mostly in those with 1:1 conversion. A limited sampling strategy utilizing three blood samples (0, 1, 3 h post‐dosing of Neoral formulation) provided an excellent correlation with actual drug exposure (r = 0.977). Enhanced CSA absorption with the microemulsion formulation. results in increased drug exposure that may reduce GFR in some patients who undergo 1:1 dose‐ratio conversion. The Neoral formulation that permits a more effective, consistent, and predicatble absorption of CSA may represent a great advantage in order to prevent acute and possibly chronic rejections. Efforts have to be made to find optimal therapeutic range and dosing schedule for this new formulation, which may be facilitated by using the limited sampling approach to predict AUC after only three‐point sampling.